Polystyrene film elements and subbing compositions therefor



Feb. 3, 1959 c. B. STARCK 2,872,313

POLYSTYRENE FILM ELEMENTS AND SUBBING COMPOSITIONS THEREFOR Filed Feb.14, 1958 GELAUN AND CELLULOSE N/T RATE ORIENTED POLYSTYRENE F/LM BASEGELAT/N AND SILVER HAL/DE GELAT/N AND CELLULOSE N/TRAT E ORIENTEDPOLYSTYRENE F/LM BASE GELAT/N AND S/LVER HAL/DE GELAT/N AND CELLULOSEN/TRAT E ORIENTED POLKSTYRENE F/LM BASE a\\\\\\\\\\\\\w GELAT/IVA/VDCELLULOSE N/TRAT E GELATYN AND S/LVER HAL/DE GELA77N AND CELLULOSEN/TRATE /O V///% OR/EIVTED POLYSTYRE/VE F/LM BASE zL\ GEL AT/N ANDCELLULOSE xv/r/m r5 GEL/177A! LAYER CLEMENS B. STA/PCK INVENTOR.

ATTORNEY 8 AGENT United States Patent if POLYSTYRENE FILM ELEMENTS ANDSUBBING COMPOSITIONS THEREFOR {Siemens Bernard Starch, Rochester,Eastman Kodak Company, Rochester, N. Y., a corporation of New JerseyApplication February 14, 1958, Serial No. 715,295 r f.

a 18 Claims. ('Cl. 96-437) This invention relates to photographic film'or she'et 2,8 7 2,3 18 Patented Feb. 3,1959

However, such negatives produced from the materials available heretoforehave not been entirely satisfactory in the above respects. Also, it issometimes necessary to reduce or intensify'the negative images, and heretoo, the prior art materials have shown serious separation of I theemulsion from the film base in the regions where the Y., assignor toconventional reducing and intensifying solutions have been applied.

I have found that a very effective subbing composition for'orientedpolystyrene sheeting and film base is obtained "I by dispersing gelatinand cellulose nitrate in a solvent elements wherein the film base is ahighly hydrophobic 1.;

mixturecontaining-in addition to low boiling solvents from 520% byweight of the subbing composition of a' higher. boiling solvent, i. e.having a boiling points'ubstantiallyi above 120" C., from the groupconsisting of acetonyl acetone, butyl carbitol acetate cm oc mo'c mococma mixture of 70-80% of a-methyl benzyl alcohol and 30-20% ofacetophenone, but more especially mesityl 7 oxide. The subbing layeradheres firmly to the film of the above kind having an improvedanchoring substratum (commonly known as a subbing layer) between thefilm base and the light-sensitive water-permeable colloid layer oremulsion disposed thereon, preferably a gelatin'o silver halide emulsionlayer.

Oriented polystyrene sheeting has many desirable physical propertieswhich make it attractive for use as a photographic film base. However,it is highly hydrophobic, and in order to secure adhesion to it of anormal type of. hydrophilic gelatino-silver halide emulsion layer, itis' necessary to provide one or more intermediate anchoring layers,so-called subbing or substratum layers. Such substratum layers areintended to provide firm adhesion of the polystyrene film base to thegelatin emulsion layer. To secure anchorage to the polystyrene filmba's'e, however, it is necessary to applya coating th'ereover from asolution of a suitable anchoring material in a solvent medium which hasat least some solvent or swelling action on the polystyrene but whichaction is insuflicient to distort the surface of the film base. Whilevarious compositions and combination of layers have been proposed j forthis purpose, none have proven entirely satisfactory in actualcommercial practice. For example,

when solvents such as toluol, ethylene dichloride, methylene dichloride,acetone, etc.,. which are known to be active Solvents orswelling'solvents for polystyrene were used in the substratumcompositions in varying concentrations, it

has been found that bad cra'zing of the film base surfacedeveloped, andwhen such subbed materials were .overcoated withemulsion, adhesion ofthe emulsion to the film base was found to be very poor. In addition,the.

solvents penetrated into the film base and destroyed dimensionalstability. Also; the final photographic film element so produced showedserious skidding and spontaneous stripping after processing and drying.Another serious disadvantage of prior art photographic elements is inconnection with graphic arts and cartographic processes wherein theexposed and processed negatives are subjected to scribing to producesharp lines in the printed images, for example, in aerial'surveyingwherein latitude and longitude lines are produced by scribing such linesthrough the emulsion layer of the exposed and processed negative. Itwill be obvious thatin this kind of process theemulsion must adheretightly to the film base so that the scribed lines will have clean edgeswithout any peeling basefahd when ove'rcoated with a light-sensitiveemulsion, preferably a gelatino-silver halide emulsion layer, the filmelement thus obtained retains all of the desirable physical propertiesof oriented polystyrene film base with none of the above mentioneddisadvantages of emulsion'skidding and stripping found with relatedprior art photographic elements.

' It is, accordingly, an object of the invention to provide anoveland'useful composition that adheres strongly to orientedpolystyrene film base or sheets. Another objectis to provide a highstability photographic element wherein'a layer of the above compositionis coated directly on at least one side of oriented polystyrene filmbase and wherein at least one of the coated sides is overcoated with alayer of light-sensitive emulsion, more particularly with agelatino-silver halide emulsion layer. Anotherobject is to provide aprocess for preparing these novel materials. Other objects will becomeapparent hereinafter.

In accordance with the invention, my novel photographic elementsareprepared by applying a subbing composition on oriented polystyrene filmbase, preferably on both surfaces, dryingthe subbed film base and thenapplying on or more light sensitive compositions over at least one ofthe subbed surfaces, followed by drying the element so formed.Preferably only one of the subbed surfaces is overcoated with alight-sensitive layer, and the other-subbed surface is coated with anon-sensitive gelatin solutionwhich mayralso contain antistaticmaterials, filter dyes, are, which primarily serve to prevent curling ofthe film base and also avoids static charge'build up,

. essentially of from 0.407175% by weight of gelatin and back re'fl ection, and the like.

Suitable subbing.compositions of the invention consist from0.032-,0.l40% by weight of cellulose nitrate in a solvent, combinationof acetone, lower saturated aliphatic alcohols of 1 to 3 carbon atomssuch as methyl alcohol,

ethyl alcohol and isopropyl alcohol, and from 5-20% by weight of atleastone Off the previously mentioned suitable higher boiling solvents,and more particularly mesityl oxide; A conventional acid dispersingagent for gelatin such as acetic acid is employed in an amount varyingfrom0.041.0% based on the total weight of the sub- I bingcomposition,together with from 0.8-3.5% of water,

even after prolonged storage of the scribed negative.

to promote dispersion of thegelati'n. Preferably, there is alsoincorporateda hardener for the gelatin varying in amount from a trace0.001%) to not more than 0.026%, preferably in the form of CrCl -6H O.

Typical subbing compositions of the invention come smears within theranges specified in the following general for- The cellulose nitrate ispreferably a relatively low viscosity type having a nitrogen content of11% by weight and being 80-90% soluble in alcohol. For optimum emulsionadhesion and film base appearance, a composition containing on a weightbasis about 0.8% of gelatin and 0.064% of cellulose nitrate, and theremainder of the solvent combination containing mesityl oxide, as thehigh boiling component has been found to be the most satisfactory. Whenthe solids are reduced below 0.4% of gelatin and 0.032% of cellulosenitrate per 100 parts of the solvent combination or increasedsubstantially above the specified upper limits of 1.75% of gelatin and0.1492 of cellulose acetate, poor bonding of the subbing compositionlayer to the oriented polystyrene film base results. However, not allhigher boiling solvents are effective in obtaining the objects of theinvention. For example, I have found that related solvents such as3-heptanone,4-, methyl-Z-pentanone and hexachloro-1,3-butadi ene whensubstituted as the higher boiling solvent component in the aforesaidcompositions give very unsatisfactory subbing compositions, i. e., theadherence of the gelatino-silver halide emulsion layer to the orientedpolystyrene base is from poor to bad in any concentration under testingand use conditions, while other higher boiling solvents such as2,6-dimethyl-4-heptanone, dibutyl carbitol and mixtures of acetophenoneand wmethyl benzyl alcohol wherein the latter component is less than70%, showonly slightly better adherence under the sameconditions ascompared to those giving from poor to bad results.

While the subbing compositions of the invention can be applied to theoriented polystyrene film base by any conventional method such asdipping, spraying, etc., the

preferred method is to use a bead coating technique wherein the filmbase moves continuously and progressively under an applicationhopperfThe temperature of thesubbing composition and the film base surface atpoint of application is advantageously maintained at a range of fromabout 50-120 F. After drying, a coating of gelatino-silver halide isapplied over the subbed surface, also in a. continuous manner, as wellasany other coatings such as the mentioned backing layers on the reverse;

side which also has been subbed as above. The completed photographicelement is then dried under conventional conditions of temperature andhumidity. I

Film elements of the kind described above are shown in sectional viewsin the accompanying drawing.

As shown in Fig. 1 an oriented polystyrene film base is coated with asubbing layer 11 comprising gelatin and cellulose nitrate. In thepreferred form, layer 11 also contains a hardener for the gelatin, e. g.chromic chloride.

The element shown in Fig. 2 is the same as that shownin Fig. 1, exceptthat a gelatino-silver halide 12 is coated over the subbing layer 11.

The element shown in Fig. 3 is the same as that shown in Fig. 2, exceptthat the subbing layer 11 is also coated on the back of the orientedpolystyrenefilm base 10.

'The element shown in Fig. 4 is the preferred element and is the same asFig. 3, except that an additional layer 13 of gelatin iscoated oversubbing layerll on the back surface of theoriented polystyrenefilm base,10'. Layer 4 13 is intended primarily to prevent curling, but may alsocontain suitable antistatic materials, filter dyes, and the like.

The manner of practicing my invention is further illustrated by thefollowing examples:

Example 1 An oriented polystyrene film base was coated on both surfaceswith the following subbing solution, the components being given aspercent by weight:

ethyl alcohol, suiiicient to make a total of After drying, one or" thecoated surfaces was overcoated with an ordinary gelatino-silver halideemulsion and the other surface was overcoated with an aqueous gelatinsolution containing no silver halide. On drying and curing, no curl wasobserved. The photographic element thus obtained, on testing, showedhighly satisfactory physical characteristics such as good flexibilitywithout brittleness, and was outstanding as to dimensional stability andfirm adherence of the emulsion layer to the film base. No stripping oremulsion skidding occurred when samples of the element were exposed andprocessed. The negatives produced had good definition and were readilyscribed on the emulsion side to give clean lines, and the printsreproduced therefrom showed sharp, welldefined lines. -On storing thenegatives for several weeks at relatively low humidity, no edge peelingof the emulsion from the film base was observed, and the prints madematched perfectly those prepared prior to storing. The tests indicated,accordingly, that the photographic element produced as above describedwas eminently suited for graphic arts and cartographic operations.

Example 2 surfaces with the following subbing composition, theproportions being given as percent by weight.

Percent Gelatin 1.75 Acetic acid- 1.00 Chrornic chloride (CrCl -6H O)0.046 Cellulose nitrate 0.14 Acetone 10.0 Isopropyl alcohol 10.0Acetonyl acetone 20.0 Water 3.5

Methylalcohol, sufiicient to make a total of 100% After drying, one ofthe coated surfaces was overcoated withan ordinary gelatino-silverhalide emulsion and the other coated surface was overcoated with anaqueous gelatin solution containing no silver halide. On drying,the-element obtained showed no tendency to curl. It showed excellentphysical characteristics and underwent all the tests without anyindication of stripping or skidd spi h emuls l y r- Example 4 Thisexample was carried exactly the same as Example 1, except that 5% byweight of butyl carbitol acetate was substituted for the mesityl oxidein the subbing composition. The photographic element obtained alsoshowed satisfactory resistance to stripping and skidding of the emulsionunder test conditions simulating actual intended use practices.

Example 5 This example was carried out exactly the same as Example 1,except that 5% by weight of a mixture of 25% acetophenone and 75% ofa-methyl benzyl alcohol was substituted for the mesityl oxide. Nostripping or skidding of the emulsion was observed under the testconditions which followed the processes generally employed in graphicarts and cartographic practices.

The invention further contemplates a subbing composition of theaforementioned kind modified by the addition of resins which inthemselves will adhere to oriented polystyrene film base. Polybutylmethacrylate represents a resin ofthis kind. When added in aconcentration of 50% of the weight of the gelatin employed it promotesbonding of the subbing layer to the film base. However, a greater amountof active solvent is required to cause it to dissolve to a homogeneousmixture. While at the higher concentrations of active solvents theadhesion appears to be excellent, the subbed base tends to be hazy andshows some crazing. Accordingly, only limited uses are contemplated forsuch subbed oriented polystyrene sheeting.

What is claimed is:

1. A coating composition for oriented polystyrene sheeting consistingessentially of 0.40-1.7S% by weight of gelatin, 0.032-0.140% by weightof cellulose, nitrate, 0.83.5% by weight of Water, -30% by weight ofacetone, 10-30% by weight of isopropyl alcohol, -75% by weight of methylalcohol, and 5-20% by weight of a higher boiling solvent selected fromthe group consisting of mesityl oxide, acetonyl acetone, butyl carbitolacetate,

' and a mixture of from 70-80% by weight of u-methyl benzyl alcohol and30-20% by weight of acetophenone.

2. A coating composition according to claim 1, wherein the said higherboiling solvent is mesityl oxide.

3. A coating composition according to claim 1, wherein the said higherboiling solvent is acetonyl acetone.

4. A coating composition according to claim 1, wherein the said higherboiling solvent is butyl carbitol acetate.

5. A coating composition according to claim 1, wherein the said higherboiling solvent is a mixture of 70-80% by weight of a-methyl benzylalcohol and 30-20% by weight of acetophenone.

6. An oriented polystyrene film base coated on at least one surface witha coating composition consisting essentially of 0.40-1.75 by weight ofgelatin, 0.032-0.140% by weight of cellulose nitrate, 0.8-3.5 by weightof water, 10-30% by weight of acetone, 10-30% by weight of isopropylalcohol, 15-75% by weight of methyl alcohol, and 5-20% by weight of ahigher boiling solvent selected from the group consisting of mesityloxide, acetonyl acetone, butyl carbitol acetate, and a mixture of from7080% by weight of a-methyl benzyl alcohol and 30- by weight ofacetophenone.

7. An oriented polystyrene film base coated on at least one surface witha coating composition according to claim 6, wherein the said higherboiling solvent is mesityl oxide.

8. An oriented polystyrene film base coated on at least one surface witha coating composition according to claim 6, wherein the said higherboiling solvent is acetonyl acetone.

9. An oriented polystyrene film base coated on at least one surface witha coating composition according to claim 6, wherein the said higherboiling solvent is butyl carbitol acetate.

, 6 10. An oriented "polystyrenefilm base coated on at least one surfacewith a coating composition according to claim 6, wherein the said higherboiling solvent is a mixture of 70-80% by weight of a-methyl'benzylalcohol and'30-20% by weight of acetophenone.

11. A photographic element comprising an oriented polystyrene film basecoated on at least one surface with a coating composition consistingessentially of 0.40-1.75% by weight of gelatin, 0.032-0.140% by weightof cellulose nitrate, 0.8-3.5 by weight of water, 10-30% by weight ofacetone, 10-30% by weight of isopropyl alcohol, 15- 75 by weight ofmethyl alcohol, and 5-20% by weight of a higher boiling solvent selectedfrom the group consisting of mesityl oxide, acetonyl acetone, butylcarbitol acetate, and a mixture of from 70-80% by weight of a-methylbenzyl alcohol and 30-20% by weight of acetophenone, and having agelatino-silver halide emulsion layer coated directly over one of saidcoated surfaces of the said film base.

12. A photographic element comprising an oriented polystyrene film basecoated on at least one surface with a coating composition according toclaim 11 wherein the said higher boiling solvent is mesityl oxide, andhaving a gelatino-silver halide emulsion layer coated directly over oneof said coated surfaces of said film base.

13. A photographic element comprising an oriented polystyrene film basecoated on both surfaces with a coating composition consistingessentially of 0.40-1.75% by weight of gelatin, 0.032-0.140% by Weightof cellulose nitrate, 0.8-3.5 by weight of water, 10-30% by weight ofacetone, 10-30% by weight of isopropyl alcohol, 15-75% by weight ofmethyl alcohol, and 5-20% by weight of a higher boiling solvent selectedfrom the group consisting of mesityl oxide, acetonyl acetone, butylcarbitol acetate, and a mixture of from 70-80% by Weight of a-methylbenzyl alcohol and 30-20% by weight of acetophenone, and having agelatino-silver halide emulsion layer coated directly over 7 one of saidcoated surfaces of said film base, and hav- 1 ing a non-sensitivegelatin composition coated directly over the other of said coatedsurfaces of said film base.

14. A photographic element comprising an oriented polystyrene film basecoated on both surfaces with a coating composition according to claim13, wherein the said higher boiling solvent is mesityl oxide, and havinga gelatinio-silver halide emulsion layer coated directly over one ofsaid coated surfaces of said film base, and having a non-sensitivegelatin composition coated directly over the other of said coatedsurfaces of said film base.

15. A photographic element comprising an oriented polystyrene film basecoated on both surfaces with a coating composition according to claim13, wherein the said higher boiling solvent is acetonyl acetone, andhaving a gelatino-silver halide emulsion layer coated di- 7 rectly overone of said coated surfaces of said film base, and having anon-sensitive gelatin composition coated directly over the other of saidcoated surfaces of said film base.

16. A photographic element comprising an oriented polystyrene film basecoated on both surfaces with a coating composition according to claim13, wherein the said higher boiling solvent is butyl carbitol acetate,and having a' gelatino-silver halide emulsion layer coated directly overone of said coated surfaces of said film base, and having anon-sensitive gelatin composition coated directly over the other of saidcoated surfaces of said film base. p

17. A photographic element comprising an oriented polystyrene film basecoated on both surfaces with a coating composition according to claim13, wherein the said higher boiling solvent is a mixture of 70-80% byweight of a-methyl benzyl alcohol and 30-20% by weight of acetophenone,and having a gelatino-silver halide emulsion layer coated directly overone of said 7 coated surfaces of said film base, and having anonsensitive gelatin composition coated directly over the other of saidcoated surfaces ofsaid filrn base.

18. A process for preparing a photographic element comprising anoriented polystyrene as a film base which comprises coating bothsurfaces of said film base with a coating composition consistingessentially of GAO-1.75% by eight of gelatin, 0.032-O.140% by Weight ofcellulose nitrate, Oil-3.5% by weight of Water, 1030% by weight ofacetone, 10-30% by Weight of isopropyl alcohol, 15-75% by weight ofmethyl alcohol, and

540% by weight of a higher boiling solvent selected from the groupconsisting of mesityl oxide, acetonyl acetone, butyl carbitol acetate,and a mixture of from.

70-80% by Weight of ot-methyl benzyl alcohol and 30-20% by Weight ofacetophenone, and subsequently coating a layer of gelatino-silver halideover one of said coated surfaces, and coating a non-sensitive gelatincomposition over the other of said coated surfaces.

No references cited

13. A PHOTOGRAPHIC ELEMENT COMPRISING AN ORIENTED POLYSTYRENE FILM BASECOATED ON BOTH SURFACES WITH A COATING COMPOSITION CONSISTINGESSENTIALLY OF 0.40-1.75% BY WEIGHT OF GELATIN, 0.032-0.140% BY WEIGHTOF CELLULOSE NITRATE, 0.8-3.5% BY WEIGHT OF WATER, 10-30% BY WEIGHT OFACETONE, 10-30% BY WEIGHT OF ISOPROPYL ALCOHOL, 15-75% BY WEIGHT OFMETHYL OXIDE, ACETONYL 5-20% BY WEIGHT OF A HIGHER BOILINGSOLVENTSELECTED FROM THE GROUP CONSISTING OF MESITYL OXIDE, ACETONYL ACETONE,BUTYL CARBITOL ACETATE, AND A MIXTURE OF FROM 70-80% BY WEIGHT OFA-METHYL BENZYL ALCOHOL AND 30-20% BY WEIGHT OF ACETOPHENONE, AND HAVINGA GELARINO-SILVER HALIDE EMULSION LAYERCOATED DIRECTLY OVER ONE OF SAIDCOATED SURFACES OF SAID FILM BASE, AND HAVING A NON-SENSITIVE GELANTINCOMPOSITION COATED DIRECTLY OVER THE OTHER OF SAID COATED SURFACES OFSAID FILM BASE.